1. Field of the Invention
This invention relates to a method for preparing tomato-based food products having a pH of less than 4.6 and in particular, it relates to a method for preparing shelf-stable, temperature-sensitive, tomato-based food products having a pH of less than 4.6.
2. Discussion of the Related Art.
Shelf-stable food products are of ever-increasing popularity. Consumers appreciate the convenience of purchasing food products and not having to worry about the products spoiling, before the products can be consumed. But consumers also demand that the shelf-stable products have the taste, appearance, and texture of their freshly prepared counterparts. Consequently, there is a continuing need for processes that provide both long-term stability against changes in the character of the products and, of course, stability against microbial contamination.
High-acid foods are foods that naturally have a pH less than 4.6. Acidified food are foods to which a food acceptable acid, such as citric acid or acetic acid, has been added to bring the pH to below 4.60. Among the most popular high-acid and acidified foods are tomato-based foods, including ketchup and barbeque sauces, as well as salsas, spaghetti sauces, and pizza sauces, which all can contain fresh ingredients, such as tomatoes, onions, bell peppers, and the like, in a tomato base. To ensure that such food products have an adequate shelf-life and do not spoil before they are ultimately consumed, the products can be heat-treated. Heat-treatment typically involves subjecting the food products to elevated temperatures, for example, tomato-based food products are generally pasteurized and hot-filled into individual containers at temperatures in excess of 195.degree. F. High temperature heat-treatment, however, has serious drawbacks. In particular, the use of high temperatures adversely affect the texture, flavor, color, and nutrient quality of the food product.
It is also known to add preservatives to shelf-stable foodstuffs to prolong shelf-life. One such preservative is nisin, an antimicrobial substance produced by certain strains of Streptococcus lactis. Nisan is an antimicrobial agent that has been used to control bacterial spoilage in both heat-processed and low-pH foods, including salsa, tomato sauce, and canned vegetables. Nisin, by itself, does not to improve the texture, flavor, and color in temperature-sensitive, high-acid or acidified foods that have been thermally treated at elevated temperatures.
Accordingly, there has existed a definite need for a simple and effective method for preparing temperature-sensitive, shelf-stable, high-acid or acidified, tomato-based foods, such as ketchup, salsas, and barbeque, spaghetti and pizza sauces. There has existed a still further need for such a process that preserves the texture, appearance, nutrient quality, and flavor of freshly their freshly prepared counterparts, while protecting against microbial contamination. The present invention satisfies these and other needs and provides further related advantages.